Subject: 240V Line

[Edward R Cole]

First best wishes for a Merry Christmas and Happy New Year!

I think I chose a 25A twist-lock receptacle for my 4KV-1A PS.  I ran
8-3 plus No. 10 safety ground cable because I did want to split out
120vac to two duplex outlets using two separate 20A breakers.  That
gives me 120v for my station 12v-50A supply and a Motorola 26v/12v PS
that powers my HF 300w and 222-MHz 150w PA's.  120v also goes to the
HVPS and last outlet powers my mini mw oven (for heating coffee,
etc.).  I will add another 25A outlet for the 50v-50A PS for my 1100w
6m linear that is planned to be added, soon.

Having the 240v 20A breaker in the room is handy if the PS trips it
off.  Took me about half a day to run it.

The bedroom that serves as my ham shack has standard No. 12 romex run
to the outlets that power the computer stuff, lights and some small
wall warts, wx station, 24v PS for my relays.  Outlets are typical 15A rating.

My home has a 4-foot high crawl space so running the 240v line was
easy.  I drilled a hole in the floor of the utility room where the
main load center is located and ran PVC conduit from box to floor.  I
did the same thing in the bedroom next to  the wall where my radio
rack is installed.  The HVPS outlet is wired with a short run of No.
10 thru conduit to standard metal surface 4x4 box with single 25A outlet.

I see about 3v sag in 240vac when I key my 8877 at 1400w (draws
3.8kV@700ma on anode).  the 240v run is about 35-foot.  The extra
remnant of the 8-3 wire was used to wire my 6500w Honda generator
into a 200A cutover switch mounted next to my meter box.

I have just enough of the 8-3 left to use for wiring 28vdc at my dish
for my 1296 300w amplifier from the 18A Astron PS that sits in a
wx-tight box under the 16-foot dish.

73, Ed
----------
From: Jim Brown <[hidden email]>
To: Reflector Elecraft <[hidden email]>
Subject: [Elecraft] 240V Line
Message-ID: <[hidden email]>
Content-Type: text/plain; charset=utf-8; format=flowed

Installing a 240V outlet is not a big deal unless the construction of
your home makes it difficult to run the cable. Barring that, a competent
electrician should be able to do that in a half day; a difficult run
could double the work. All that is required is a pair plus a Green wire.
If you also want 120V outlets from the same circuit, you'll need another
conductor for the neutral.

A single 20A 120/240V circuit will run all the ham gear in most
stations, even for SO2R. If you're smart, you'll use #10 copper, 20A
outlets, and a 20A breaker. While #10 is rated for 30A, our stations
don't need 30A, but the bigger copper will reduce the voltage drop.

There are MAJOR advantages to running all the gear in our stations from
outlets that share the same Green wire, or outlets whose Green wires are
bonded together. See http://k9yc.com/GroundingAndAudio.pdf

73, Jim K9YC


73, Ed - KL7UW
http://www.kl7uw.com
     "Kits made by KL7UW"
Dubus Mag business:
     [hidden email]

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[Jim Brown-10]

On Thu,12/25/2014 8:34 AM, Edward R Cole wrote:
> Having the 240v 20A breaker in the room is handy if the PS trips it off.

Something would have to break to trip a 20A breaker in a legal,
single-operator ham station. I'm set up for SO2R with a pair of legal
limit Ten Tec Titan amps running on the same circuit. In SO2R, only one
transmits at a time. But on occasion, I've hit a string of dits to tune
one amp while the other is transmitting. I've never tripped a breaker. I
have occasionally blown fuses on the amps.

Remember that most breakers are designed to not trip until current has
exceeded their limit by some percentage, and for some time. A big
over-current (like 35A) will trip a 20A breaker very quickly, but 25A
will take a while longer.

73, Jim K9YC
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[Vic Rosenthal]

Yup. Last year I was changing the primary taps on a massive 3.5 kVA Dahl
transformer on a homebrew amplifier. Instead of connecting the line to
the 0V and 220V taps as I intended, I connected it to the 220V and 240V
taps.

When I turned it on, it popped

1. The 15A breaker in the amplifier,
2. The 20A breaker on the wall where my 240V line (#10) came in, and
3. The 30A breaker at the service entrance.

It also temporarily welded the contacts of the contactor in the
amplifier. It did NOT blow any diodes (maybe because they were 6A10's)
or capacitors. I can only imagine what the secondary voltage might have
been if the diodes and capacitors hadn't looked like a short in the
instant (it seemed instantaneous to me) before the breakers went.

Don't do this, but if you do it's good to have lots of breakers.

On 25 Dec 2014 18:34, Edward R Cole wrote:
> Having the 240v 20A breaker in the room is handy if the PS trips it off.

--
73,
Vic, 4X6GP/K2VCO
Rehovot, Israel
http://www.qsl.net/k2vco/
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